The present invention relates generally to agricultural harvesters and, more specifically, to header height control for such harvesters.
A self-propelled harvester such as a combine usually includes a header for engaging a number of transversely spaced rows or a substantial width of crop. To maintain the header at the desired level above the ground or below the crop heads for efficient harvesting and for header grounding avoidance, an automatic header height control system is provided which typically includes a mechanical feeler or an acoustic sensor or similar non-contact ground sensing device mounted on the header. Examples of previously available devices are shown in U.S. Pat. Nos. 6,173,614; 5,704,200; 5,463,854; 5,155,984 and 4,171,606. U.S. Pat. No. 4,776,153 shows a header height control system with a plurality of feelers and a tilt control.
Although available control systems generally provide good position control in most situations and relieve the operator of the tedious job of manually adjusting height or tilt with changing ground and crop conditions, several problems exist with the systems. Hydraulic power requirements and material stress levels often are high when the lift systems are providing a fast response. The systems often fail to respond in time to avoid inefficient crop pickup, excessive crop material intake, or grounding and damage of the header. System response time is a problem when the harvester is travelling at relatively high speeds, such as when operating in field conditions wherein crop yield is low, and when the harvester is operating in fields having substantial ground contour changes. Tilt response time at high speeds or in fields with very uneven surface contours is often too slow for headers having automatic tilting systems to maintain the header generally parallel to the ground such as shown in the aforementioned U.S. Pat. No. 4,776,153. Header grounding and damage, and improper header operating height, result in decreased productivity. When the harvester is crossing depressions such as valleys, gullies or swales, the header can be grounded and damaged before the lift system can respond to the sudden rise in the ground surface. Grounding is a particular problem when the front harvester wheels are in a depression and the header is adjacent a raised surface area. Near the apex of a hill or mounded area, the header is often too high and misses crop since the system cannot respond quickly to the abrupt change in ground surface.
It is therefore an object of the present invention to provide an improved header position control system for a combine or other harvester. It is a further object to provide such a control system which overcomes most or all of the aforementioned problems.
It is another object of the invention to provide a header position control system having smoother response with reduced hydraulic power requirements and less material stress, particularly during high speed operations in fields with abruptly changing ground contours, than at least most previously available systems.
It is a further object to provide a header position control system for a harvester which reduces or eliminates the incidences of header over- or under-height when depressions or rises in the ground surface are encountered. It is still another object of the invention to provide a header position control system which predicts and compensates for the ground irregularities encountered by the ground wheel support structure and the header.
It is another object to provide an improved harvester height control system wherein desired header height and/or tilt position for a forward location is calculated in advance of the header and any ground sensing transducer on the header arriving at the location. It is still another object to provide such a system which is complementary to any conventional sensing transducer on the header and which can provide a predictive contour history over the entire width of the header.
It is yet a further object to provide an improved harvester position control system for maintaining cut height within a preselected range of the crop heads to reduce non-crop material throughput and increase productivity.
The system for improved header postition control includes a sensor, such as a crop edge detector, mounted on the harvester for measuring ground contour of an area a substantial distance in front of the header and providing a surface profile indication over the whole platform width. The sensor includes a transmitter mounted on the harvester for radiating a signal across an area approximately equal to the width of the path to be traversed by the header, and a receiver which receives reflected signals. Travel times of the signals from a radiated area in the path are utilized to estimate ground contour of that area. The ground contour can be estimated directly by scanning the area with a crop penetrating signal, such as a high frequency radar signal, and receiving reflections from the ground. By scanning with a laser device such as a rotatable crop edge sensor, signals are reflected from the crop and provide a crop contour signal. The crop contour signal can be used to maintain the header a preselected distance below the crop heads to reduce throughput and increase harvester productivity. The crop contour signal can also be used to estimate ground surface profile.
An on-board processor calculates the desired header height and/or tilt for an area in advance of the harvester reaching the area. The early ground contour/crop contour measurements enable the height control and tilt control, if the combine is so equipped, to begin to make corrections in advance of the header reaching the area for smoother adjustments with less stress on harvester components. Hydraulic power requirements and header reaction response time are reduced, features which are particularly important when the harvester is operated at relatively high speeds or in fields with abruptly changing ground surface contours. The contour prediction may also used to compensate for effects of header attitude changes resulting from harvester ground wheels or tracks riding on that contour.
These and other objects, features and advantages of the present invention will become apparent to one skilled in the art upon reading the following detailed description in view of the drawings.